Illegal fentanyl — a potent painkiller — can be so dangerous that even the smallest amount breathed in or absorbed through the skin can have fatal consequences. It’s often mixed with heroin.

Investigators were looking into the situation, but suspected Banks came into contact with the powerful drug somewhere in his community of Overton, the hub for Miami’s opioid crisis due to the high rate of heroin and fentanyl sales, the Herald reported.

Miami-Dade State Attorney Katherine Fernandez Rundle said it was likely a combination of the two that led to the child’s death.

“At this point, we have every reason to believe that their preliminary findings are that it was a mixture of heroin and fentanyl that killed this little boy,” Fernandez Rundle said at a news conference Tuesday, according to NBC.

Authorities are currently trying to determine how Banks came into contact with the deadly drug.

So far, they believe that he may have come into contact with the drug after swimming at a neighborhood pool.

“We believe that it was somewhere between the park or the pool or the sidewalk, or maybe he touched something,” Fernandez Rundle said.

Send your thoughts and prayers to the Bank’s family. Share this story on social media in order to help make parents aware of how dangerous fentanyl is.